#include <vector>

class Matrix
{
	// Expected a ':' after protected, to declare list of protected variables
protected:
    unsigned int rows_;
    unsigned int cols_;
    std::vector<double> storage_;

public:
    Matrix();

    Matrix( Matrix const & other );

	// a ';' was omitted at the end of the below line
    Matrix( unsigned int const & rows, unsigned int const & cols );

	// a ',' was omitted between the row and col arguments
    double & operator()( unsigned int const & row, unsigned int const & col );

    double const & operator()( unsigned int const & row, unsigned int const & col ) const;

	// The 'r' was omitted in the second "Matrix"
    Matrix & operator+=( Matrix const & other );

	// an useless ':' was uesd at the beginning of this line  
    Matrix operator+( Matrix const & other ) const;
};